Field of the Invention
The present invention relates to a rotary machine including a damper collar.
Such a collar of the present invention is particularly suitable for being incorporated in a turbine engine, for example, in order to provide damping to the rotary portion of the turbine engine, in particular when passing through critical speeds.
Description of the Related Art
The rotary machine in question mainly comprises a rotary portion that may be a rotor and a stationary portion that may be a stator, together with at least one bearing having a stationary ring and a movable ring in order to support and guide the rotary portion in rotation. In such a machine, it is difficult to pass through critical speeds and ensure radial stability at high speeds of rotation given the low levels of external damping that are available. High levels of vibration can lead to the bearing(s) being overloaded and to contacts being made between the rotary portion and the stationary portion.
Damper collars are already known that are used for providing the rotors of turbine engines with damping. In particular, a type of collar is known that is made from a strip of steel sheet that is positioned around the stationary ring of the bearing. Such damper collars are shaped so as to present circumferential corrugations. On assembly, the corrugations are compressed a little between the stationary ring of the bearing and an outer casing of said rotary machine. Thus, the radial movements of the stationary ring of the bearing are absorbed by deforming the corrugations of the collar, which corrugations then behave like springs. That is why a collar of that type is referred to as a “tolerance ring” or a “resilient spacer”. Such prior art collars are obtained by using shaping methods that involve subjecting the strip of sheet metal to heat treatment and then to die stamping, followed by further heat treatment so that the sheet metal of the strip becomes springy once more. That succession of fabrication steps is not always very precise and prevents damper collars being produced that are identical, all having the same dimensional and mechanical characteristics. Furthermore, that succession of steps also does not make it possible to estimate accurately the dimensional and mechanical characteristics of such collars.